Add sync error logging, extend error flash, fix unload saves

- Log workforce sync errors to backend stdout so they appear in docker logs
- Extend error flash from 5s to 15s so errors are readable
- Replace sendBeacon (POST-only) with keepalive fetch (PUT) on unload —
  sendBeacon was hitting 404s on all three unload saves

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/node_modules/lucide-react/dist/esm/icons/wifi-pen.mjs

@@ -0,0 +1,25 @@
+/**
+ * @license lucide-react v1.24.0 - ISC
+ *
+ * This source code is licensed under the ISC license.
+ * See the LICENSE file in the root directory of this source tree.
+ */
+
+import createLucideIcon from '../createLucideIcon.mjs';
+
+const __iconNode = [
+  ["path", { d: "M2 8.82a15 15 0 0 1 20 0", key: "dnpr2z" }],
+  [
+    "path",
+    {
+      d: "M21.378 16.626a1 1 0 0 0-3.004-3.004l-4.01 4.012a2 2 0 0 0-.506.854l-.837 2.87a.5.5 0 0 0 .62.62l2.87-.837a2 2 0 0 0 .854-.506z",
+      key: "1817ys"
+    }
+  ],
+  ["path", { d: "M5 12.859a10 10 0 0 1 10.5-2.222", key: "rpb7oy" }],
+  ["path", { d: "M8.5 16.429a5 5 0 0 1 3-1.406", key: "r8bmzl" }]
+];
+const WifiPen = createLucideIcon("wifi-pen", __iconNode);
+
+export { __iconNode, WifiPen as default };
+//# sourceMappingURL=wifi-pen.mjs.map